Recovery of formation fluid such as petroleum from a subterranean formation is frequently difficult when the subterranean formation is comprised of one or more incompetent or unconsolidated sand layers or zones. Sand particles in the incompetent or unconsolidated sand zone move or migrate into the well bore during the recovery of formation fluids from that zone, or sand particles move away from the well during the injection of secondary or tertiary recovery fluids into the formation. In the instance of recovering fluid from the formation, the movement of sand into the well bore can cause the well to cease production of fluids. Also, small sand particles can plug small opening and porous masses formed around the well bore for the purpose of restraining the flow of sand, such as screens or slotted liners which are frequently placed in wells for this purpose. Not only can fluid production be reduced or even stopped altogether, if sand particles flow through the well to the surface, considerable mechanical problems can result from passage of abrasive sand particles through pumps and other mechanical devices.
Many techniques have been described in the prior art for preventing or decreasing the flow of sand into a well during petroleum production, including the use of sand screens, filters, and perforated or slotted liners. These prior art attempts have been successful in some limited instances, but have not always been entirely satisfactory for a number of reasons. Mechanical devices usually restrain only the larger particle sand and are not completely effective for the purpose of restraining or preventing the flow of fine particles from the formation into the well and ultimately to the surface. Furthermore, the devices interfere with various types of completions and workover operations. Additionally, many of the devices were not able to withstand the combination of high temperatures and high pH often encountered.
Serious problems have been encountered in attempting to use conventional production strings in conjunction with enhanced recovery techniques involving steam injection, acidizing, or workover fluids. Where high temperature steam, acid, or hot water under high flow rates contact a conventional string, it has been fond that such strings are quickly eroded away or dissolved and must therefore be replaced at frequent intervals.
Therefore, what is needed is a device which can be used as a means of formation fines control which is resistant to shock, replaceable, versatile, and which can be used in conjunction with harsh conditions encountered with enhanced oil recovery techniques.